And pertinent - so many butterflies in our garden this last week! Mostly Caper Whites on their mysterious migration: ‘Breeds in vast numbers on trees and shrubs of the genus Capparis (Wild Caper, Mock Orange) and enormous numbers of Caper Whites sometimes aggregate on coastal headlands before flying out to sea.’ Queensland Museum

Thank you for your comments and your fascinating question, John. I believe the haiku needs the word "in" as it makes the middle line a pivot on which lines one and three can swing. Why do you think the haiku would be better without the preposition?